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Community Response to the CWCB Desil!nation and Approval Process The community was contacted initially by letter. In a follow up phone call a meeting was arranged with local officials to present the CWCB's proposal to designate and approve approximate floodplain information for Boone. A meeting was conducted by CWCB staff on April 17, 1996. Local officials in attendance included the mayor, two town council members and the building official. Everyone was very receptive to the CWCB's designation and approval of the county's floodplain information. ENGINEERING METHODS Hydrologic Analvsis Hydrology information for the stream with an approximate floodplain delineation on Boone's FHBM should be estimated in accordance with the CWCB's "Guidelines for Determining 100- Year Flood Flows for Approximate Floodplains" (Guidelines). However, the 100-year flow for the streams with approximate floodplains cannot be estimated by utilizing the regression equation for Arkansas River Basin, Subregion Ark-l because the drainage basin size for the Unnamed Tributary to Sand Arroyo is less than 25 square miles which is less than the lower limit for the Arkansas River Basin, Subregion Ark-I. Additionally, the CWCB has not developed a procedure for determining hydrologic information for local drainage attributed to nearby irrigation canals. Therefore, a detailed hydrologic and hydraulic study is required prior to any floodplain development. A procedure for determining hydrology information for approximate floodplains of lakes, ponds, and local drainages has not been established. The. hydrologic methodology developed in the Guidelines is appropriate for designation and approval of approximate floodplain information and for use in simple floodplain analyses for development such as open space, agriculture, farm bridges, pole barns, and individual single residential structures. The methodology is not appropriate for development involving residential subdivisions greater than 50 lots or occurring on sites greater than 5 acres, commercial construction, industrial construction, construction of public transportation facilities, or construction of flood control facilities. The Town of Boone should regulate the approximate floodplains on a case-by-case basis subject to a detailed hydrologic and hydraulic analysis performed by a professional engineer, in accordance with the determinations of the Colorado Water Conservation Board regarding the applicability of the Guidelines. Hydraulic Analysis The hydraulic analysis for the preparation of the FHBM likely consisted of interpretation of USGS quadrangle mapping by HUD's engineering consultant, along with telephone discussions with local officials. The telephone discussions addressed any historic flood problems that may